The intracranial pressure-volume relationship following decompressive hinge craniotomy compared to decompressive craniectomy-a human cadaver study.

Abstract

Decompressive hinge craniotomy (DHC) is an alternative treatment option to decompressive craniectomy (DC) for elevated intracranial pressure (ICP). The aim of this study was to characterize the difference in pressure-volume relationship between DHC and DC. We compared the intracranial pressure-volume relationship in a human cadaver model following either DHC, DC, or fixing of the bone plate by titanium clamps. We inserted an intracranial expandable device in two human cadaver specimens, performed either DHC, DC, or bone plate fixation, and gradually increased the intracranial volume while measuring ICP. Following DHC, we also performed CT-scans at pre-defined intervals. Before ICP exceeded a threshold of 20mmHg, a fixed bone plate tolerated an increase of 130ml of intracranial volume, while DHC and DC allowed an increase of 190ml and 290ml, respectively. CT-derived calculations following DHC determined that the increase in intracranial volume at ICP 22mmHg was 65ml, the maximal increase of intracranial volume was 84ml, the maximal bone displacement was 21mm, and the bone plate volume to be 82ml. Manual stress test of the hinged bone plate did not allow misalignment or intracranial displacement of the bone plate. DHC increases the intracranial volume by up to 84ml and allows for approximately 60ml increase of intracranial volume before ICP exceeds 20mmHg. This indicates, when comparing with results from previous studies of herniation volumes, that DHC will be sufficient in many patients with head injury or cerebral infarction with treatment refractory intracranial hypertension.